Beriberi refers to a cluster of symptoms caused primarily by a nutritional deficit in Vitamin B1 (thiamine). Beriberi has conventionally been divided into three separate entities, relating to the body system involved (nervous or cardiovascular) or age of patient (infantile). Beriberi is one of several thiamine-deficiency related conditions, which may occur concurrently, including Wernicke's encephalopathy, Korsakoff's syndrome, and Wernicke-Korsakoff syndrome.
Historically, Beriberi has been endemic in regions dependent on what is variously referred to as polished, white, or de-husked rice. This type of rice has its husk removed in order to extend its lifespan, but also has the unintended side-effect of removing the primary source of thiamine.

Beriberi disease is due to vitamin B1 (thiamine) deficiency. It manifests as neurological disorders, peripheral paralysis, psychosis, weakened heart and impaired circulatory system and results in heart failure and death.